add a way for callback to disable itself

The idea is that some plugin would not be called in some
specific case, and the callback should decide by itself.

Having a way to globally disable it is much cleaner than
disabling every method one by one on the plugin side.

My use case is for fedora-infrastructure that cannot be run
from git checkout since it try to connect to the message bus,
but another case would be to bootstrap infrastructure, or to
run the code on a test servers without having all the callback
infrastructure setup.
add test for the disabling of callback plugins
switch to DictCursor
Add detail to copy module validate argument

This clarifies the validate command argument and makes it clear that if
it is present, it must include the '%s' argument for the path to the
temporary file to validate.
nova compute fix regex in instance name
Fix timeout bug in firewalld module
Template sudo_user via with_items
Merge pull request #4421 from jkleckner/copy-module-validate-doc

Add detail to copy module validate argument
Merge pull request #4422 from bennojoy/nova1

nova compute fix for instance name regex issue
Merge pull request #4423 from localvoid/firewalld-fix_timeout

Fix timeout bug in firewalld module
Correct typo
Add caching to pattern enumeration

Inventory._hosts_in_unenumerated_pattern()

Was TODO: cache this logic so if called a second time the result is not
recalculated
Merge pull request #4429 from sergevanginderachter/cache_pattern_enumeration

Add caching to pattern enumeration
Fix 'hg module fails with: AttributeError: 'AnsibleModule' object has no attribute 'parames''
Fix Hg.__init__(...) reading value from self.hg_path
Merge pull request #4432 from madsweitling/devel

Fix typo and broken "Hg.__init__" in 'hg' module
toned down the error message for unconfigured master/slave
Implement a |changed filter plugin
make changed filter understand results lists
Merge pull request #4437 from sergevanginderachter/changed_filter

Implement a |changed filter plugin